Ceteris paribus, base stealing doesn't make sense. But baseball is a game played by humans and even if it weren't, there are a large number of variables that don't go into the simple analysis.

For example: The members of the defending team adopt fielding positions based on a maximum potential for fielding a hit ball. But if there is even a threat of a stolen base attempt, the defense must change their positioning accordingly, affecting their ability to field a ball put into play.

If a player does make an attempt to steal a base, at least one defender must begin to change their positioning before the hitter has even had a chance to hit the ball. If they do not, they will not make it to the base in time to receive the throw from the catcher and either the throw will not occur or it will go out into the outfield and the runner may advance another base. Alternatively, the hitter may actually hit the ball and the ball may go to an area that it is statistically likely to go, where a defender would have been but for the stolen base attempt. What was to be an out is now a hit and the runner, having a head start because of their stolen base attempt, is able to advance further than they normally would have been able to. Because the hitter hit the ball, this situation does not get recorded in the statistics as a stolen base attempt!

Baseball is really a fascinating game to think about!